This invention relates to a zero-clearance firebox which may be used with either solid fuels, particularly wood, or liquid fuels, such as natural gas. A zero-clearance firebox has outer surfaces which may be placed in direct contact with combustible building materials, and as such may be placed against a wall. The firebox disclosed herein can be used in both new construction and remodeling.
Many zero-clearance fireplaces are disclosed in the prior art.
U.S. Pat. No. 4,607,611 to J. S. Rice et al., discloses a solid fuel burning stove enclosed in a metal box. The exterior walls of the stove, which is identified as a Trailmaster 4NI, manufactured by Appalachian Stove, is blanketed with thermal insulation which may be a ceramic fiber. The stove is fitted into a metal box, the inner surfaces of which are also lined with thermal insulation. A metal shield is positioned between the stove and the metal box which at least partially surrounds the stove, to create air spaces between the insulation on the metal box and the shield as well as between the shield and the insulation on the exterior walls of the stove.
Another zero-clearance fireplace, disclosed in U.S. Pat. No. 4,287,871 to G. Schumann et al., consists, essentially, of three concentric metal boxes with air spaces therebetween. The inner metal box is the firebox which is surrounded by a second metal box to define an air space for the circulation of air to be warmed. The outer surface of the second metal box is covered with a sheath of insulation material. A third metal box surrounds the second metal box on the sides, back and top. Cool room air circulates between the second metal box and the third metal box to cool the fireplace.
U.S. Pat. No. 4,169,458 to W. S. Shaw, also discloses what is described as a zero-clearance fireplace which, in cross section, also consists of three concentric metal boxes. The device includes a conventional single walled metal firebox having closeable doors and a flue adopted to communicate with a chimney, enclosed within two metal boxes which define passages for the circulation of air, whereby heat is exchanged between the walls of the metal boxes and the circulating air so that the outer surface of the outermost box remains sufficiently cool to permit installation adjacent combustible structural members. In an alternative embodiment an additional chamber is provided, surrounding all the aforementioned chambers, which can provide a dead air insulating space.
U.S. Pat. No. 4,153,036 to T. F. Billmeyer et al., discloses another complicated metal manufactured fireplace. The fireplace includes a firebox at least partially surrounded by a housing to define an air space therebetween which has a relatively low air inlet and a relatively high air outlet. The firebox is constructed of metal walls sandwiching refractory block. The outer housing is also constructed of refractory block sandwiched between metal walls.
A zero-clearance wood burning stove is disclosed in U.S. Pat. No. 4,369,761 to C. S. Burnette. The stove includes three distinct wall structures, defining an inner most combustion chamber 12, an intermediate air circulating chamber and an outer most chamber which has mineral wool insulation therein.
Finally, U.S. Pat. No. 2,875,747 to W. G. Fish discloses a prefabricated fireplace of metal sheets and "cementitious" panels. The firebox of the fireplace is formed of spaced sheets of metal, having an air space there between.
As can be seen from the foregoing, all are relatively complicated structures with at least three boxes, some of which define a tortious path of air circulation in an attempt to cool the air within a mid-chamber and warm the air in the room. None provide for a direct and simple exchange of warmed air with cooled air through a single opening in a zero-clearance fireplace. None provide for the simple finishing techniques to accept plaster or stucco to accommodate fashionable architectural styles, such as the southwestern United States adobe style.
It is thus an object of the present invention to provide a zero-clearance firebox of much simpler construction, which can be installed in direct contact with combustible building materials, either along a wall or situated in a corner.
Yet another object of the invention is to provide a zero-clearance firebox that has an efficient hot air/cool air exchange rate.
It is still another object of the invention to provide a zero-clearance firebox that can accept either solid or liquid fuels.
It is another object of the invention to provide a firebox to which additional materials can be easily attached to form a fireplace of the desired external ornamental configuration.
It is still another object of the invention to provide a firebox with both the insulating capabilities and the appearance of masonry or adobe, but unlike adobe and masonry, and because of its light weight, can be installed on existing floors, without the need for a reinforced support or slab.
It is an object of the invention to provide a firebox with zero-clearance that is easily and quickly installed because there is no waiting for masonry to cure.
It is still another object of the invention to provide a functional zero-clearance firebox that can accommodate flexibility of exterior ornamental design and finishing.